<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <!--[if lt IE 9]>
      <script src="https://cdn.jsdelivr.net/npm/html5shiv@3.7.3/dist/html5shiv.min.js"></script>
      <script src="https://cdn.jsdelivr.net/npm/respond.js@1.4.2/dest/respond.min.js"></script>
    <![endif]-->
    <link rel="stylesheet" href="bootstrap/css/bootstrap.min.css">
    <style>
        .login {
            width: 100px;
            height: 40px;
        }
        
        [class^="container"] {
            background-color: pink;
        }
    </style>
    <title>Document</title>
</head>

<body>
    <button type="button" class="btn btn-success login">登录</button>
    <div class="container">123</div>
    <div class="container-fluid">123</div>
</body>

</html>